The principal research focus is to analyze longitudinal changes in functioning among BLSA subjects. The aims are to characterize intra- individual changes in 14 domains of activity and to study how these changes vary by sociodemographic and medical factors. The data for these analyses are derived from the "Activity Questionnaire II". It has been filled out by BLSA subjects at each visit since 1966. Subjects estimate the amount of time they spend on numerous specific activities, ranging from personal care to leisure. This data set is unique for its time stretch (up to 25 years for some subjects) and its content (the comprehensive scope of activities). Analyses on this data set include examinations of the cross- sectional, longitudinal, and secular patterns by age and gender. Cross- sectional analyses reveal consistent age and gender differences for participation in and time spent doing various activities, especially work, housework, childcare, and various discretionary activities.